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21CNCStudio

@21CNCStudio

Wall-Mount Enclosure Reveal & CO Sensor Update

Hey everyone! 👋

Quick reminder: Please leave all your questions and comments right here under this update! It's the only way I can reliably find and answer them. 🙏

📦 Wall-Mount Enclosure — What Do You Think?

So... how did it turn out? I think it looks pretty decent!

Despite the compact size, I managed to fit all the sensors inside — including the CO sensor and space for a future DAC module (for controlling ventilation fans or even smart lighting).

Not bad for something that hangs on the wall, right? 😄
For the upcoming stretch goal enclosures, I'm going to add some visual flair. I think you're going to like what I have in mind. 😏

🧪 CO Sensor Update: DFRobot SEN0466

After testing several options, I went with the DFRobot SEN0466 carbon monoxide sensor.

It's been integrated into Aura's system and running for 3 days straight now. So far, so good! ✅
By the way, I've updated the standard desktop enclosure design so you won't have to reprint the whole thing if you decide to add a CO sensor or DAC module later.

Just swap out the back cover — that's it!

But... there's one annoying thing.

The cable situation. 🤦♂️

I can't find a Gravity to STEMMA QT cable (JST-PH to JST-SH) shorter than 200mm anywhere. Actually, they basically don't exist except for this one option.

Your options:

Use the included cable and solder a STEMMA QT connector — takes 5 minutes, pretty straightforward
Hunt for a compatible cable — good luck, you'll need it

Why I'm annoyed about the 200mm cable:

Longer I2C cables add capacitance and can cause signal integrity issues. Ideally, you'd add pull-up resistors for stability... but let's be honest, nobody is going to do that. 😅

I've done everything I can in firmware to compensate, but occasionally (like once every 1-2 hours) there's a tiny touchscreen hiccup. We're talking 0.1% chance you'd even notice — but it drives me crazy because I want everything to work perfectly.

(Yes, I have a problem. I know.) 🤓

The Bigger Picture:

There aren't really any other good CO sensor options that integrate this cleanly. The SEN0466 isn't cheap (~$60-70), but when we're talking about carbon monoxide detection, I don't think saving $20-30 is worth it.

I'll give the final "go ahead and buy this sensor" confirmation in the next update once I'm 100% confident — but right now it's looking like our best (and only) realistic choice.

Stay tuned for the next update!

Questions about the wall-mount or CO sensor? Drop them below! 💬

#Questions #Crowdfunding Feature #Project Aura

Comment (26)

Pinned by Poster

@21CNCStudio : If you've already assembled your device without an enclosure and flashed the firmware from GitHub — awesome! But please remember: These are delicate electronics! Don't poke the boards with your fingers while they're running. They're vulnerable to static discharge and physical stress. If something stops working after you've been poking around... well, that's probably why. 😅 Pro tips: Handle boards by the edges only Don't touch components while powered on (seriously, just... don't) Power it off first Ground yourself before touching anything (touch a metal surface first) I know it's tempting to tap the screen while holding the board in your other hand, but trust me — wait until it's safely in the enclosure. And most importantly: If you catch any bugs, glitches, or weird behavior — please report them! That's exactly what this testing phase is for. Drop a comment here with details (screenshots help!) and I'll investigate. Your feedback makes the firmware better for everyone. 🙏

The poster has replied

@21CNCStudio : @JerryJF : I'm really sorry this situation happened. I had never seen the 8MB Flash variant until I started getting feedback on GitHub — even the official Waveshare store only sells the 16MB version. If I had known about these 8MB variants being sold elsewhere, I would have emphasized the Flash size requirement much more clearly in the documentation. That said, the BOM link I provided does point directly to the official Waveshare store and the correct 16MB Flash board, so I assumed that would prevent confusion. You might also want to check AliExpress — they often have the correct 16MB version with free or low-cost shipping to Europe. Again, I apologize for the headache this has caused.

@JerryJF : Your latest update about the display is much more complicated apparently at least for us in Europe. Mouser and Digikey to not carry it. I got mine on Amazon and it has the same 25948 number as the link but yes it only has 8MB Flash. It is from XDH Tech in France. The ones listed by BerryBase and TinyTronics only list 8MB Flash on their website. The Portuguese distributor Botnroll listing for 25498 also only lists 8MB Flash. I have now ordered direct from Waveshare. With shipping and cheapest shipping it is just below 37Euro. Once VAT is added by PT customs and handling by the Post it will be over 51Euro or 61USD.

@Mitch_in_Wilts : Not sure if this is the right place. In response to update 15. Digikey in UK now have 27 SEN66 Breakout in stock as of 1630 on 26 Feb 2026 (email in stock). Loving this project. Keep up the good work.

The poster has replied

@21CNCStudio : Thank you for the heads up — that's great news! Really appreciate you sharing this. Hopefully stock starts improving across other regions too. Glad you're enjoying the project!

@lorinnpro : woow, I’m impresed!! good job💯👍🏼

The poster has replied

@21CNCStudio : Thank you!

@jakecovert : Can I ask if you could / would support the Adafruit BMP585 sensor? (the other ones were / are sold out). Thanks in advance. :-D

The poster has replied

@21CNCStudio : Please wait a couple of days — I'm working on an alternative BOM with support for more pressure sensor options, including the BMP585. I'll publish an update soon!

@user_535144287 : The SFA30 sensor is currently backordered on Digi-key and Mouser. I just got an update that my backorder isn't going to deliver until Aug. Is there an alternate sensor or a source you have for getting them?

The poster has replied

@21CNCStudio : I'm working on an alternative BOM with more readily available components. I'll try to publish an update by the end of the week.

@Quito : In the #9 Update (14-02-2026 - Power Supply Requirements) You said it is important good quality USB power adapter (5V 2A minimum) and Quality USB cable. In the case of power adapters you can trust what is printed on it (although some manufacturers are not very reliable), with the cables it is even more complicated. Given the importance and in order to rule out possible problem factors, could Aura be made to test the electrical current received? maybe in a debug menu?

The poster has replied

@Quito : @21CNCStudio : That sounds like enough to keep you from going crazy if you don't realize the problem is the cable =D I love people who are meticulous. Keep it up! Regards from Spain =)

@21CNCStudio : Great suggestion! The short answer is: we can't measure USB current directly — that requires dedicated hardware (shunt resistor + IC like INA219) which isn't on the Aura PCB. Measuring USB 5V voltage also isn't possible without a hardware voltage divider. However, Aura already does power quality monitoring behind the scenes — the ESP32 has a built-in brownout detector that fires when voltage drops below ~2.4V on the 3.3V rail. If your USB cable or adapter causes a voltage drop under load, Aura will record a "brownout reset" and show it in the boot diagnostics screen. A future firmware update could expose this more prominently — showing a brownout event counter and a warning like "Power issue detected — check your USB cable/adapter". This is something I'm considering for the debug menu. No hardware changes needed.

@JerryJF : OK I admit cable connectors are a mystery to me. Is this the right cable for the CO Sensor and if so is it too short. It is on Aliexpress. 4399 STEMMA QT/Qwiic JST 4 Pin Cable 30mm.

@user_2499767840 : I may have just not seen it in the posting, but I am wondering if there will be the ability for alerts sent to your phone for things like changes in pressure or high levels of pollen or something like that? Would that have to be through something like the home assistant?

The poster has replied

@21CNCStudio : For push notifications and alerts, the recommended approach is through Home Assistant. Aura publishes all sensor data via MQTT, so you can set up HA automations to send notifications to your phone when CO₂ spikes, PM levels rise, or any other threshold is crossed. This gives you complete flexibility without requiring any cloud service from me.

@user_2499767840 : Consider me a know nothing.. I really dont know where else to source these items myself. I am in the US. And right now I have the 3(maybe just 2) cables, the clock, and the breakout for the SEN66 ordered on backorder from digikey. From the looks of things they wont be shipped until mid to late march. Wouldnt consider that a problem for me per say, but for anybody else like me I imagine that those backorder times will just get worse with the amount of interest in the project.

The poster has replied

@21CNCStudio : I'm actively monitoring the situation and posted a recent update about this. I'm looking into alternative manufacturer options in case there are delays from Adafruit suppliers. The most important thing: make sure you get the SEN66 sensor — that's the heart of the project. Everything else (breakout boards, cables, accessories) has more flexibility and alternative sources if needed. I'll keep everyone updated if I find good alternative suppliers for any components.

@adamscybot : May I suggest a discussion thread about availability is instead created on github discussions on the repo, and that is also linked from the main crowdfunding description? I beleive discussion about it here (linking to third party vendors) is limited by the terms. Not to mention makerworld comments mechanism doesnt work well as a super usable source of truth. A potentially bette alternative would be community discord server

The poster has replied

@21CNCStudio : That’s actually a great idea 👍 Creating a dedicated GitHub Discussions thread for availability makes a lot of sense, especially long-term. My only hesitation is that not everyone in the crowdfunding campaign is familiar with GitHub or comfortable using it, so I don’t want to move important information somewhere that part of the audience won’t see. But I agree that MakerWorld comments aren’t ideal as a “single source of truth.” I’ll think about the best structure — maybe linking both GitHub and an additional channel.

@Sn0rrii : Would be nice to have a complete or easy to connect cable with connector without soldering for the CO sensor. I already bought this sensor.

The poster has replied

@Sn0rrii : @21CNCStudio : ok great but didnt find any ready cable on Amazon. maybe you habe a link for it.

@21CNCStudio : Yes — there is a ready-made cable option that works without soldering. The only downside is that it’s 200 mm long, and you’ll need to swap the pins. After that, it works fine — so you can definitely avoid soldering altogether 👍